81222791 has 8 divisors (see below), whose sum is σ = 87590160. Its totient is φ = 74872512.

The previous prime is 81222703. The next prime is 81222797. The reversal of 81222791 is 19722218.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-81222791 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81222797) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6656 + ... + 14378.

It is an arithmetic number, because the mean of its divisors is an integer number (10948770).

Almost surely, 2^81222791 is an apocalyptic number.

81222791 is a deficient number, since it is larger than the sum of its proper divisors (6367369).

81222791 is a wasteful number, since it uses less digits than its factorization.

81222791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8545.

The product of its digits is 4032, while the sum is 32.

The square root of 81222791 is about 9012.3687785177. The cubic root of 81222791 is about 433.0711995806.

The spelling of 81222791 in words is "eighty-one million, two hundred twenty-two thousand, seven hundred ninety-one".